NEW YORK — Federal investigators on Sunday were examining the wreckage of a single-engine plane that crashed on a beach in Coney Island, killing all four people on board, including two high school students who were going to graduate on Tuesday.

The Cessna 172S plummeted to the ground Saturday after its engine apparently stalled while circling above the beach, witnesses said. No one on the ground was injured.

Pilot, plane probed
The cause of the crash was not immediately known, but authorities were looking at the plane’s systems and whether the pilot was at fault, said National Transportation Safety Board investigator Todd Gunther.

“We’re looking into all factors,” he said.

Police identified the passengers as Courtney Block, 38, and his daughter, Danielle Block, 18, both of Benwood, W.Va., and family friend JoBeth Marie Gross, 18, of McMechen, W.Va. The pilot was Endrew Allen, 32, of Queens.

The teenagers and their parents were on a weekend trip celebrating the end of final exams and Tuesday’s graduation at Bishop Donahue High School in McMechen. The flight was part of a sightseeing tour for aspiring pilots, Mayor Michael Bloomberg said Saturday.

Crash kills several ‘musketeers’Principal Rene Roy said Danielle and Joel-Beth Marie played softball, volleyball and basketball and had been in several school plays. They were part of a group of friends dubbed “the four musketeers.”

Another “musketeer” initially had been on the plane with her two friends, but she got sick and asked the pilot to take her back to the airport, Roy said. After the pilot returned, Courtney Block got on the plane in her place.

The crash, which stunned sunbathers on the beach, occurred within sight of the Wonder Wheel attraction at the world-renowned beach, home to the Cyclone rollercoaster and the Astroland amusement park.